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Revision 1.108 by root, Sat May 10 00:22:02 2008 UTC vs.
Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC

1=head1 NAME 1=head1 => NAME
2 2
3AnyEvent - provide framework for multiple event loops 3AnyEvent - provide framework for multiple event loops
4 4
5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops 5EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6 6
15 my $w = AnyEvent->timer (after => $seconds, cb => sub { 15 my $w = AnyEvent->timer (after => $seconds, cb => sub {
16 ... 16 ...
17 }); 17 });
18 18
19 my $w = AnyEvent->condvar; # stores whether a condition was flagged 19 my $w = AnyEvent->condvar; # stores whether a condition was flagged
20 $w->send; # wake up current and all future recv's
20 $w->wait; # enters "main loop" till $condvar gets ->send 21 $w->recv; # enters "main loop" till $condvar gets ->send
21 $w->send; # wake up current and all future wait's
22 22
23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT) 23=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24 24
25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen 25Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26nowadays. So what is different about AnyEvent? 26nowadays. So what is different about AnyEvent?
57as those use one of the supported event loops. It is trivial to add new 57as those use one of the supported event loops. It is trivial to add new
58event loops to AnyEvent, too, so it is future-proof). 58event loops to AnyEvent, too, so it is future-proof).
59 59
60In addition to being free of having to use I<the one and only true event 60In addition to being free of having to use I<the one and only true event
61model>, AnyEvent also is free of bloat and policy: with POE or similar 61model>, AnyEvent also is free of bloat and policy: with POE or similar
62modules, you get an enourmous amount of code and strict rules you have to 62modules, you get an enormous amount of code and strict rules you have to
63follow. AnyEvent, on the other hand, is lean and up to the point, by only 63follow. AnyEvent, on the other hand, is lean and up to the point, by only
64offering the functionality that is necessary, in as thin as a wrapper as 64offering the functionality that is necessary, in as thin as a wrapper as
65technically possible. 65technically possible.
66 66
67Of course, if you want lots of policy (this can arguably be somewhat 67Of course, if you want lots of policy (this can arguably be somewhat
108 108
109=head1 WATCHERS 109=head1 WATCHERS
110 110
111AnyEvent has the central concept of a I<watcher>, which is an object that 111AnyEvent has the central concept of a I<watcher>, which is an object that
112stores relevant data for each kind of event you are waiting for, such as 112stores relevant data for each kind of event you are waiting for, such as
113the callback to call, the filehandle to watch, etc. 113the callback to call, the file handle to watch, etc.
114 114
115These watchers are normal Perl objects with normal Perl lifetime. After 115These watchers are normal Perl objects with normal Perl lifetime. After
116creating a watcher it will immediately "watch" for events and invoke the 116creating a watcher it will immediately "watch" for events and invoke the
117callback when the event occurs (of course, only when the event model 117callback when the event occurs (of course, only when the event model
118is in control). 118is in control).
237 237
238Although the callback might get passed parameters, their value and 238Although the callback might get passed parameters, their value and
239presence is undefined and you cannot rely on them. Portable AnyEvent 239presence is undefined and you cannot rely on them. Portable AnyEvent
240callbacks cannot use arguments passed to signal watcher callbacks. 240callbacks cannot use arguments passed to signal watcher callbacks.
241 241
242Multiple signal occurances can be clumped together into one callback 242Multiple signal occurrences can be clumped together into one callback
243invocation, and callback invocation will be synchronous. synchronous means 243invocation, and callback invocation will be synchronous. Synchronous means
244that it might take a while until the signal gets handled by the process, 244that it might take a while until the signal gets handled by the process,
245but it is guarenteed not to interrupt any other callbacks. 245but it is guaranteed not to interrupt any other callbacks.
246 246
247The main advantage of using these watchers is that you can share a signal 247The main advantage of using these watchers is that you can share a signal
248between multiple watchers. 248between multiple watchers.
249 249
250This watcher might use C<%SIG>, so programs overwriting those signals 250This watcher might use C<%SIG>, so programs overwriting those signals
278C<fork> the child (alternatively, you can call C<AnyEvent::detect>). 278C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279 279
280Example: fork a process and wait for it 280Example: fork a process and wait for it
281 281
282 my $done = AnyEvent->condvar; 282 my $done = AnyEvent->condvar;
283
284 AnyEvent::detect; # force event module to be initialised
285 283
286 my $pid = fork or exit 5; 284 my $pid = fork or exit 5;
287 285
288 my $w = AnyEvent->child ( 286 my $w = AnyEvent->child (
289 pid => $pid, 287 pid => $pid,
293 $done->send; 291 $done->send;
294 }, 292 },
295 ); 293 );
296 294
297 # do something else, then wait for process exit 295 # do something else, then wait for process exit
298 $done->wait; 296 $done->recv;
299 297
300=head2 CONDITION VARIABLES 298=head2 CONDITION VARIABLES
301 299
302If you are familiar with some event loops you will know that all of them 300If you are familiar with some event loops you will know that all of them
303require you to run some blocking "loop", "run" or similar function that 301require you to run some blocking "loop", "run" or similar function that
312Condition variables can be created by calling the C<< AnyEvent->condvar 310Condition variables can be created by calling the C<< AnyEvent->condvar
313>> method, usually without arguments. The only argument pair allowed is 311>> method, usually without arguments. The only argument pair allowed is
314C<cb>, which specifies a callback to be called when the condition variable 312C<cb>, which specifies a callback to be called when the condition variable
315becomes true. 313becomes true.
316 314
317After creation, the conditon variable is "false" until it becomes "true" 315After creation, the condition variable is "false" until it becomes "true"
318by calling the C<send> method. 316by calling the C<send> method (or calling the condition variable as if it
317were a callback, read about the caveats in the description for the C<<
318->send >> method).
319 319
320Condition variables are similar to callbacks, except that you can 320Condition variables are similar to callbacks, except that you can
321optionally wait for them. They can also be called merge points - points 321optionally wait for them. They can also be called merge points - points
322in time where multiple outstandign events have been processed. And yet 322in time where multiple outstanding events have been processed. And yet
323another way to call them is transations - each condition variable can be 323another way to call them is transactions - each condition variable can be
324used to represent a transaction, which finishes at some point and delivers 324used to represent a transaction, which finishes at some point and delivers
325a result. 325a result.
326 326
327Condition variables are very useful to signal that something has finished, 327Condition variables are very useful to signal that something has finished,
328for example, if you write a module that does asynchronous http requests, 328for example, if you write a module that does asynchronous http requests,
329then a condition variable would be the ideal candidate to signal the 329then a condition variable would be the ideal candidate to signal the
330availability of results. The user can either act when the callback is 330availability of results. The user can either act when the callback is
331called or can synchronously C<< ->wait >> for the results. 331called or can synchronously C<< ->recv >> for the results.
332 332
333You can also use them to simulate traditional event loops - for example, 333You can also use them to simulate traditional event loops - for example,
334you can block your main program until an event occurs - for example, you 334you can block your main program until an event occurs - for example, you
335could C<< ->wait >> in your main program until the user clicks the Quit 335could C<< ->recv >> in your main program until the user clicks the Quit
336button of your app, which would C<< ->send >> the "quit" event. 336button of your app, which would C<< ->send >> the "quit" event.
337 337
338Note that condition variables recurse into the event loop - if you have 338Note that condition variables recurse into the event loop - if you have
339two pieces of code that call C<< ->wait >> in a round-robbin fashion, you 339two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340lose. Therefore, condition variables are good to export to your caller, but 340lose. Therefore, condition variables are good to export to your caller, but
341you should avoid making a blocking wait yourself, at least in callbacks, 341you should avoid making a blocking wait yourself, at least in callbacks,
342as this asks for trouble. 342as this asks for trouble.
343 343
344Condition variables are represented by hash refs in perl, and the keys 344Condition variables are represented by hash refs in perl, and the keys
349 349
350There are two "sides" to a condition variable - the "producer side" which 350There are two "sides" to a condition variable - the "producer side" which
351eventually calls C<< -> send >>, and the "consumer side", which waits 351eventually calls C<< -> send >>, and the "consumer side", which waits
352for the send to occur. 352for the send to occur.
353 353
354Example: 354Example: wait for a timer.
355 355
356 # wait till the result is ready 356 # wait till the result is ready
357 my $result_ready = AnyEvent->condvar; 357 my $result_ready = AnyEvent->condvar;
358 358
359 # do something such as adding a timer 359 # do something such as adding a timer
365 cb => sub { $result_ready->send }, 365 cb => sub { $result_ready->send },
366 ); 366 );
367 367
368 # this "blocks" (while handling events) till the callback 368 # this "blocks" (while handling events) till the callback
369 # calls send 369 # calls send
370 $result_ready->wait; 370 $result_ready->recv;
371
372Example: wait for a timer, but take advantage of the fact that
373condition variables are also code references.
374
375 my $done = AnyEvent->condvar;
376 my $delay = AnyEvent->timer (after => 5, cb => $done);
377 $done->recv;
371 378
372=head3 METHODS FOR PRODUCERS 379=head3 METHODS FOR PRODUCERS
373 380
374These methods should only be used by the producing side, i.e. the 381These methods should only be used by the producing side, i.e. the
375code/module that eventually sends the signal. Note that it is also 382code/module that eventually sends the signal. Note that it is also
378 385
379=over 4 386=over 4
380 387
381=item $cv->send (...) 388=item $cv->send (...)
382 389
383Flag the condition as ready - a running C<< ->wait >> and all further 390Flag the condition as ready - a running C<< ->recv >> and all further
384calls to C<wait> will (eventually) return after this method has been 391calls to C<recv> will (eventually) return after this method has been
385called. If nobody is waiting the send will be remembered. 392called. If nobody is waiting the send will be remembered.
386 393
387If a callback has been set on the condition variable, it is called 394If a callback has been set on the condition variable, it is called
388immediately from within send. 395immediately from within send.
389 396
390Any arguments passed to the C<send> call will be returned by all 397Any arguments passed to the C<send> call will be returned by all
391future C<< ->wait >> calls. 398future C<< ->recv >> calls.
399
400Condition variables are overloaded so one can call them directly
401(as a code reference). Calling them directly is the same as calling
402C<send>. Note, however, that many C-based event loops do not handle
403overloading, so as tempting as it may be, passing a condition variable
404instead of a callback does not work. Both the pure perl and EV loops
405support overloading, however, as well as all functions that use perl to
406invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407example).
392 408
393=item $cv->croak ($error) 409=item $cv->croak ($error)
394 410
395Similar to send, but causes all call's wait C<< ->wait >> to invoke 411Similar to send, but causes all call's to C<< ->recv >> to invoke
396C<Carp::croak> with the given error message/object/scalar. 412C<Carp::croak> with the given error message/object/scalar.
397 413
398This can be used to signal any errors to the condition variable 414This can be used to signal any errors to the condition variable
399user/consumer. 415user/consumer.
400 416
401=item $cv->begin ([group callback]) 417=item $cv->begin ([group callback])
402 418
403=item $cv->end 419=item $cv->end
420
421These two methods are EXPERIMENTAL and MIGHT CHANGE.
404 422
405These two methods can be used to combine many transactions/events into 423These two methods can be used to combine many transactions/events into
406one. For example, a function that pings many hosts in parallel might want 424one. For example, a function that pings many hosts in parallel might want
407to use a condition variable for the whole process. 425to use a condition variable for the whole process.
408 426
443doesn't execute once). 461doesn't execute once).
444 462
445This is the general pattern when you "fan out" into multiple subrequests: 463This is the general pattern when you "fan out" into multiple subrequests:
446use an outer C<begin>/C<end> pair to set the callback and ensure C<end> 464use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447is called at least once, and then, for each subrequest you start, call 465is called at least once, and then, for each subrequest you start, call
448C<begin> and for eahc subrequest you finish, call C<end>. 466C<begin> and for each subrequest you finish, call C<end>.
449 467
450=back 468=back
451 469
452=head3 METHODS FOR CONSUMERS 470=head3 METHODS FOR CONSUMERS
453 471
454These methods should only be used by the consuming side, i.e. the 472These methods should only be used by the consuming side, i.e. the
455code awaits the condition. 473code awaits the condition.
456 474
457=over 4 475=over 4
458 476
459=item $cv->wait 477=item $cv->recv
460 478
461Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak 479Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462>> methods have been called on c<$cv>, while servicing other watchers 480>> methods have been called on c<$cv>, while servicing other watchers
463normally. 481normally.
464 482
475(programs might want to do that to stay interactive), so I<if you are 493(programs might want to do that to stay interactive), so I<if you are
476using this from a module, never require a blocking wait>, but let the 494using this from a module, never require a blocking wait>, but let the
477caller decide whether the call will block or not (for example, by coupling 495caller decide whether the call will block or not (for example, by coupling
478condition variables with some kind of request results and supporting 496condition variables with some kind of request results and supporting
479callbacks so the caller knows that getting the result will not block, 497callbacks so the caller knows that getting the result will not block,
480while still suppporting blocking waits if the caller so desires). 498while still supporting blocking waits if the caller so desires).
481 499
482Another reason I<never> to C<< ->wait >> in a module is that you cannot 500Another reason I<never> to C<< ->recv >> in a module is that you cannot
483sensibly have two C<< ->wait >>'s in parallel, as that would require 501sensibly have two C<< ->recv >>'s in parallel, as that would require
484multiple interpreters or coroutines/threads, none of which C<AnyEvent> 502multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485can supply. 503can supply.
486 504
487The L<Coro> module, however, I<can> and I<does> supply coroutines and, in 505The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe 506fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489versions and also integrates coroutines into AnyEvent, making blocking 507versions and also integrates coroutines into AnyEvent, making blocking
490C<< ->wait >> calls perfectly safe as long as they are done from another 508C<< ->recv >> calls perfectly safe as long as they are done from another
491coroutine (one that doesn't run the event loop). 509coroutine (one that doesn't run the event loop).
492 510
493You can ensure that C<< -wait >> never blocks by setting a callback and 511You can ensure that C<< -recv >> never blocks by setting a callback and
494only calling C<< ->wait >> from within that callback (or at a later 512only calling C<< ->recv >> from within that callback (or at a later
495time). This will work even when the event loop does not support blocking 513time). This will work even when the event loop does not support blocking
496waits otherwise. 514waits otherwise.
497 515
498=item $bool = $cv->ready 516=item $bool = $cv->ready
499 517
504 522
505This is a mutator function that returns the callback set and optionally 523This is a mutator function that returns the callback set and optionally
506replaces it before doing so. 524replaces it before doing so.
507 525
508The callback will be called when the condition becomes "true", i.e. when 526The callback will be called when the condition becomes "true", i.e. when
509C<send> or C<croak> are called. Calling C<wait> inside the callback 527C<send> or C<croak> are called. Calling C<recv> inside the callback
510or at any later time is guaranteed not to block. 528or at any later time is guaranteed not to block.
511 529
512=back 530=back
513 531
514=head1 GLOBAL VARIABLES AND FUNCTIONS 532=head1 GLOBAL VARIABLES AND FUNCTIONS
549Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model 567Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550if necessary. You should only call this function right before you would 568if necessary. You should only call this function right before you would
551have created an AnyEvent watcher anyway, that is, as late as possible at 569have created an AnyEvent watcher anyway, that is, as late as possible at
552runtime. 570runtime.
553 571
572=item $guard = AnyEvent::post_detect { BLOCK }
573
574Arranges for the code block to be executed as soon as the event model is
575autodetected (or immediately if this has already happened).
576
577If called in scalar or list context, then it creates and returns an object
578that automatically removes the callback again when it is destroyed. See
579L<Coro::BDB> for a case where this is useful.
580
554=item @AnyEvent::detect 581=item @AnyEvent::post_detect
555 582
556If there are any code references in this array (you can C<push> to it 583If there are any code references in this array (you can C<push> to it
557before or after loading AnyEvent), then they will called directly after 584before or after loading AnyEvent), then they will called directly after
558the event loop has been chosen. 585the event loop has been chosen.
559 586
560You should check C<$AnyEvent::MODEL> before adding to this array, though: 587You should check C<$AnyEvent::MODEL> before adding to this array, though:
561if it contains a true value then the event loop has already been detected, 588if it contains a true value then the event loop has already been detected,
562and the array will be ignored. 589and the array will be ignored.
590
591Best use C<AnyEvent::post_detect { BLOCK }> instead.
563 592
564=back 593=back
565 594
566=head1 WHAT TO DO IN A MODULE 595=head1 WHAT TO DO IN A MODULE
567 596
571Be careful when you create watchers in the module body - AnyEvent will 600Be careful when you create watchers in the module body - AnyEvent will
572decide which event module to use as soon as the first method is called, so 601decide which event module to use as soon as the first method is called, so
573by calling AnyEvent in your module body you force the user of your module 602by calling AnyEvent in your module body you force the user of your module
574to load the event module first. 603to load the event module first.
575 604
576Never call C<< ->wait >> on a condition variable unless you I<know> that 605Never call C<< ->recv >> on a condition variable unless you I<know> that
577the C<< ->send >> method has been called on it already. This is 606the C<< ->send >> method has been called on it already. This is
578because it will stall the whole program, and the whole point of using 607because it will stall the whole program, and the whole point of using
579events is to stay interactive. 608events is to stay interactive.
580 609
581It is fine, however, to call C<< ->wait >> when the user of your module 610It is fine, however, to call C<< ->recv >> when the user of your module
582requests it (i.e. if you create a http request object ad have a method 611requests it (i.e. if you create a http request object ad have a method
583called C<results> that returns the results, it should call C<< ->wait >> 612called C<results> that returns the results, it should call C<< ->recv >>
584freely, as the user of your module knows what she is doing. always). 613freely, as the user of your module knows what she is doing. always).
585 614
586=head1 WHAT TO DO IN THE MAIN PROGRAM 615=head1 WHAT TO DO IN THE MAIN PROGRAM
587 616
588There will always be a single main program - the only place that should 617There will always be a single main program - the only place that should
590 619
591If it doesn't care, it can just "use AnyEvent" and use it itself, or not 620If it doesn't care, it can just "use AnyEvent" and use it itself, or not
592do anything special (it does not need to be event-based) and let AnyEvent 621do anything special (it does not need to be event-based) and let AnyEvent
593decide which implementation to chose if some module relies on it. 622decide which implementation to chose if some module relies on it.
594 623
595If the main program relies on a specific event model. For example, in 624If the main program relies on a specific event model - for example, in
596Gtk2 programs you have to rely on the Glib module. You should load the 625Gtk2 programs you have to rely on the Glib module - you should load the
597event module before loading AnyEvent or any module that uses it: generally 626event module before loading AnyEvent or any module that uses it: generally
598speaking, you should load it as early as possible. The reason is that 627speaking, you should load it as early as possible. The reason is that
599modules might create watchers when they are loaded, and AnyEvent will 628modules might create watchers when they are loaded, and AnyEvent will
600decide on the event model to use as soon as it creates watchers, and it 629decide on the event model to use as soon as it creates watchers, and it
601might chose the wrong one unless you load the correct one yourself. 630might chose the wrong one unless you load the correct one yourself.
602 631
603You can chose to use a rather inefficient pure-perl implementation by 632You can chose to use a pure-perl implementation by loading the
604loading the C<AnyEvent::Impl::Perl> module, which gives you similar 633C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
605behaviour everywhere, but letting AnyEvent chose is generally better. 634everywhere, but letting AnyEvent chose the model is generally better.
635
636=head2 MAINLOOP EMULATION
637
638Sometimes (often for short test scripts, or even standalone programs who
639only want to use AnyEvent), you do not want to run a specific event loop.
640
641In that case, you can use a condition variable like this:
642
643 AnyEvent->condvar->recv;
644
645This has the effect of entering the event loop and looping forever.
646
647Note that usually your program has some exit condition, in which case
648it is better to use the "traditional" approach of storing a condition
649variable somewhere, waiting for it, and sending it when the program should
650exit cleanly.
651
606 652
607=head1 OTHER MODULES 653=head1 OTHER MODULES
608 654
609The following is a non-exhaustive list of additional modules that use 655The following is a non-exhaustive list of additional modules that use
610AnyEvent and can therefore be mixed easily with other AnyEvent modules 656AnyEvent and can therefore be mixed easily with other AnyEvent modules
622 668
623Provide read and write buffers and manages watchers for reads and writes. 669Provide read and write buffers and manages watchers for reads and writes.
624 670
625=item L<AnyEvent::Socket> 671=item L<AnyEvent::Socket>
626 672
627Provides a means to do non-blocking connects, accepts etc. 673Provides various utility functions for (internet protocol) sockets,
674addresses and name resolution. Also functions to create non-blocking tcp
675connections or tcp servers, with IPv6 and SRV record support and more.
676
677=item L<AnyEvent::DNS>
678
679Provides rich asynchronous DNS resolver capabilities.
628 680
629=item L<AnyEvent::HTTPD> 681=item L<AnyEvent::HTTPD>
630 682
631Provides a simple web application server framework. 683Provides a simple web application server framework.
632
633=item L<AnyEvent::DNS>
634
635Provides asynchronous DNS resolver capabilities, beyond what
636L<AnyEvent::Util> offers.
637 684
638=item L<AnyEvent::FastPing> 685=item L<AnyEvent::FastPing>
639 686
640The fastest ping in the west. 687The fastest ping in the west.
641 688
658 705
659=item L<Coro> 706=item L<Coro>
660 707
661Has special support for AnyEvent via L<Coro::AnyEvent>. 708Has special support for AnyEvent via L<Coro::AnyEvent>.
662 709
710=item L<AnyEvent::AIO>, L<IO::AIO>
711
712Truly asynchronous I/O, should be in the toolbox of every event
713programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714together.
715
716=item L<AnyEvent::BDB>, L<BDB>
717
718Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719IO::AIO and AnyEvent together.
720
663=item L<IO::Lambda> 721=item L<IO::Lambda>
664 722
665The lambda approach to I/O - don't ask, look there. Can use AnyEvent. 723The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
666
667=item L<IO::AIO>
668
669Truly asynchronous I/O, should be in the toolbox of every event
670programmer. Can be trivially made to use AnyEvent.
671
672=item L<BDB>
673
674Truly asynchronous Berkeley DB access. Can be trivially made to use
675AnyEvent.
676 724
677=back 725=back
678 726
679=cut 727=cut
680 728
683no warnings; 731no warnings;
684use strict; 732use strict;
685 733
686use Carp; 734use Carp;
687 735
688our $VERSION = '3.4'; 736our $VERSION = '4.03';
689our $MODEL; 737our $MODEL;
690 738
691our $AUTOLOAD; 739our $AUTOLOAD;
692our @ISA; 740our @ISA;
693 741
742our @REGISTRY;
743
694our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1; 744our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
695 745
696our @REGISTRY; 746our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
747
748{
749 my $idx;
750 $PROTOCOL{$_} = ++$idx
751 for reverse split /\s*,\s*/,
752 $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
753}
697 754
698my @models = ( 755my @models = (
699 [EV:: => AnyEvent::Impl::EV::], 756 [EV:: => AnyEvent::Impl::EV::],
700 [Event:: => AnyEvent::Impl::Event::], 757 [Event:: => AnyEvent::Impl::Event::],
701 [Tk:: => AnyEvent::Impl::Tk::],
702 [Wx:: => AnyEvent::Impl::POE::],
703 [Prima:: => AnyEvent::Impl::POE::],
704 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::], 758 [AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
705 # everything below here will not be autoprobed as the pureperl backend should work everywhere 759 # everything below here will not be autoprobed
706 [Glib:: => AnyEvent::Impl::Glib::], 760 # as the pureperl backend should work everywhere
761 # and is usually faster
762 [Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
763 [Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
707 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy 764 [Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
708 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program 765 [Qt:: => AnyEvent::Impl::Qt::], # requires special main program
709 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza 766 [POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767 [Wx:: => AnyEvent::Impl::POE::],
768 [Prima:: => AnyEvent::Impl::POE::],
710); 769);
711 770
712our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY); 771our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
713 772
714our @detect; 773our @post_detect;
774
775sub post_detect(&) {
776 my ($cb) = @_;
777
778 if ($MODEL) {
779 $cb->();
780
781 1
782 } else {
783 push @post_detect, $cb;
784
785 defined wantarray
786 ? bless \$cb, "AnyEvent::Util::PostDetect"
787 : ()
788 }
789}
790
791sub AnyEvent::Util::PostDetect::DESTROY {
792 @post_detect = grep $_ != ${$_[0]}, @post_detect;
793}
715 794
716sub detect() { 795sub detect() {
717 unless ($MODEL) { 796 unless ($MODEL) {
718 no strict 'refs'; 797 no strict 'refs';
798 local $SIG{__DIE__};
719 799
720 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) { 800 if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
721 my $model = "AnyEvent::Impl::$1"; 801 my $model = "AnyEvent::Impl::$1";
722 if (eval "require $model") { 802 if (eval "require $model") {
723 $MODEL = $model; 803 $MODEL = $model;
760 } 840 }
761 841
762 unshift @ISA, $MODEL; 842 unshift @ISA, $MODEL;
763 push @{"$MODEL\::ISA"}, "AnyEvent::Base"; 843 push @{"$MODEL\::ISA"}, "AnyEvent::Base";
764 844
765 (shift @detect)->() while @detect; 845 (shift @post_detect)->() while @post_detect;
766 } 846 }
767 847
768 $MODEL 848 $MODEL
769} 849}
770 850
780 $class->$func (@_); 860 $class->$func (@_);
781} 861}
782 862
783package AnyEvent::Base; 863package AnyEvent::Base;
784 864
785# default implementation for ->condvar, ->wait, ->broadcast 865# default implementation for ->condvar
786 866
787sub condvar { 867sub condvar {
788 bless \my $flag, "AnyEvent::Base::CondVar" 868 bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
789}
790
791sub AnyEvent::Base::CondVar::broadcast {
792 ${$_[0]}++;
793}
794
795sub AnyEvent::Base::CondVar::wait {
796 AnyEvent->one_event while !${$_[0]};
797} 869}
798 870
799# default implementation for ->signal 871# default implementation for ->signal
800 872
801our %SIG_CB; 873our %SIG_CB;
854 or Carp::croak "required option 'pid' is missing"; 926 or Carp::croak "required option 'pid' is missing";
855 927
856 $PID_CB{$pid}{$arg{cb}} = $arg{cb}; 928 $PID_CB{$pid}{$arg{cb}} = $arg{cb};
857 929
858 unless ($WNOHANG) { 930 unless ($WNOHANG) {
859 $WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1; 931 $WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
860 } 932 }
861 933
862 unless ($CHLD_W) { 934 unless ($CHLD_W) {
863 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld); 935 $CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
864 # child could be a zombie already, so make at least one round 936 # child could be a zombie already, so make at least one round
874 delete $PID_CB{$pid}{$cb}; 946 delete $PID_CB{$pid}{$cb};
875 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} }; 947 delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
876 948
877 undef $CHLD_W unless keys %PID_CB; 949 undef $CHLD_W unless keys %PID_CB;
878} 950}
951
952package AnyEvent::CondVar;
953
954our @ISA = AnyEvent::CondVar::Base::;
955
956package AnyEvent::CondVar::Base;
957
958use overload
959 '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
960 fallback => 1;
961
962sub _send {
963 # nop
964}
965
966sub send {
967 my $cv = shift;
968 $cv->{_ae_sent} = [@_];
969 (delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
970 $cv->_send;
971}
972
973sub croak {
974 $_[0]{_ae_croak} = $_[1];
975 $_[0]->send;
976}
977
978sub ready {
979 $_[0]{_ae_sent}
980}
981
982sub _wait {
983 AnyEvent->one_event while !$_[0]{_ae_sent};
984}
985
986sub recv {
987 $_[0]->_wait;
988
989 Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
990 wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
991}
992
993sub cb {
994 $_[0]{_ae_cb} = $_[1] if @_ > 1;
995 $_[0]{_ae_cb}
996}
997
998sub begin {
999 ++$_[0]{_ae_counter};
1000 $_[0]{_ae_end_cb} = $_[1] if @_ > 1;
1001}
1002
1003sub end {
1004 return if --$_[0]{_ae_counter};
1005 &{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1006}
1007
1008# undocumented/compatibility with pre-3.4
1009*broadcast = \&send;
1010*wait = \&_wait;
879 1011
880=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE 1012=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
881 1013
882This is an advanced topic that you do not normally need to use AnyEvent in 1014This is an advanced topic that you do not normally need to use AnyEvent in
883a module. This section is only of use to event loop authors who want to 1015a module. This section is only of use to event loop authors who want to
940model it chooses. 1072model it chooses.
941 1073
942=item C<PERL_ANYEVENT_MODEL> 1074=item C<PERL_ANYEVENT_MODEL>
943 1075
944This can be used to specify the event model to be used by AnyEvent, before 1076This can be used to specify the event model to be used by AnyEvent, before
945autodetection and -probing kicks in. It must be a string consisting 1077auto detection and -probing kicks in. It must be a string consisting
946entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended 1078entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
947and the resulting module name is loaded and if the load was successful, 1079and the resulting module name is loaded and if the load was successful,
948used as event model. If it fails to load AnyEvent will proceed with 1080used as event model. If it fails to load AnyEvent will proceed with
949autodetection and -probing. 1081auto detection and -probing.
950 1082
951This functionality might change in future versions. 1083This functionality might change in future versions.
952 1084
953For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you 1085For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
954could start your program like this: 1086could start your program like this:
955 1087
956 PERL_ANYEVENT_MODEL=Perl perl ... 1088 PERL_ANYEVENT_MODEL=Perl perl ...
1089
1090=item C<PERL_ANYEVENT_PROTOCOLS>
1091
1092Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1093for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1094of auto probing).
1095
1096Must be set to a comma-separated list of protocols or address families,
1097current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1098used, and preference will be given to protocols mentioned earlier in the
1099list.
1100
1101This variable can effectively be used for denial-of-service attacks
1102against local programs (e.g. when setuid), although the impact is likely
1103small, as the program has to handle connection errors already-
1104
1105Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1106but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1107- only support IPv4, never try to resolve or contact IPv6
1108addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1109IPv6, but prefer IPv6 over IPv4.
1110
1111=item C<PERL_ANYEVENT_EDNS0>
1112
1113Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1114for DNS. This extension is generally useful to reduce DNS traffic, but
1115some (broken) firewalls drop such DNS packets, which is why it is off by
1116default.
1117
1118Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1119EDNS0 in its DNS requests.
957 1120
958=back 1121=back
959 1122
960=head1 EXAMPLE PROGRAM 1123=head1 EXAMPLE PROGRAM
961 1124
972 poll => 'r', 1135 poll => 'r',
973 cb => sub { 1136 cb => sub {
974 warn "io event <$_[0]>\n"; # will always output <r> 1137 warn "io event <$_[0]>\n"; # will always output <r>
975 chomp (my $input = <STDIN>); # read a line 1138 chomp (my $input = <STDIN>); # read a line
976 warn "read: $input\n"; # output what has been read 1139 warn "read: $input\n"; # output what has been read
977 $cv->broadcast if $input =~ /^q/i; # quit program if /^q/i 1140 $cv->send if $input =~ /^q/i; # quit program if /^q/i
978 }, 1141 },
979 ); 1142 );
980 1143
981 my $time_watcher; # can only be used once 1144 my $time_watcher; # can only be used once
982 1145
987 }); 1150 });
988 } 1151 }
989 1152
990 new_timer; # create first timer 1153 new_timer; # create first timer
991 1154
992 $cv->wait; # wait until user enters /^q/i 1155 $cv->recv; # wait until user enters /^q/i
993 1156
994=head1 REAL-WORLD EXAMPLE 1157=head1 REAL-WORLD EXAMPLE
995 1158
996Consider the L<Net::FCP> module. It features (among others) the following 1159Consider the L<Net::FCP> module. It features (among others) the following
997API calls, which are to freenet what HTTP GET requests are to http: 1160API calls, which are to freenet what HTTP GET requests are to http:
1047 syswrite $txn->{fh}, $txn->{request} 1210 syswrite $txn->{fh}, $txn->{request}
1048 or die "connection or write error"; 1211 or die "connection or write error";
1049 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r }); 1212 $txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1050 1213
1051Again, C<fh_ready_r> waits till all data has arrived, and then stores the 1214Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1052result and signals any possible waiters that the request ahs finished: 1215result and signals any possible waiters that the request has finished:
1053 1216
1054 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf}; 1217 sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1055 1218
1056 if (end-of-file or data complete) { 1219 if (end-of-file or data complete) {
1057 $txn->{result} = $txn->{buf}; 1220 $txn->{result} = $txn->{buf};
1058 $txn->{finished}->broadcast; 1221 $txn->{finished}->send;
1059 $txb->{cb}->($txn) of $txn->{cb}; # also call callback 1222 $txb->{cb}->($txn) of $txn->{cb}; # also call callback
1060 } 1223 }
1061 1224
1062The C<result> method, finally, just waits for the finished signal (if the 1225The C<result> method, finally, just waits for the finished signal (if the
1063request was already finished, it doesn't wait, of course, and returns the 1226request was already finished, it doesn't wait, of course, and returns the
1064data: 1227data:
1065 1228
1066 $txn->{finished}->wait; 1229 $txn->{finished}->recv;
1067 return $txn->{result}; 1230 return $txn->{result};
1068 1231
1069The actual code goes further and collects all errors (C<die>s, exceptions) 1232The actual code goes further and collects all errors (C<die>s, exceptions)
1070that occured during request processing. The C<result> method detects 1233that occurred during request processing. The C<result> method detects
1071whether an exception as thrown (it is stored inside the $txn object) 1234whether an exception as thrown (it is stored inside the $txn object)
1072and just throws the exception, which means connection errors and other 1235and just throws the exception, which means connection errors and other
1073problems get reported tot he code that tries to use the result, not in a 1236problems get reported tot he code that tries to use the result, not in a
1074random callback. 1237random callback.
1075 1238
1106 1269
1107 my $quit = AnyEvent->condvar; 1270 my $quit = AnyEvent->condvar;
1108 1271
1109 $fcp->txn_client_get ($url)->cb (sub { 1272 $fcp->txn_client_get ($url)->cb (sub {
1110 ... 1273 ...
1111 $quit->broadcast; 1274 $quit->send;
1112 }); 1275 });
1113 1276
1114 $quit->wait; 1277 $quit->recv;
1115 1278
1116 1279
1117=head1 BENCHMARKS 1280=head1 BENCHMARKS
1118 1281
1119To give you an idea of the performance and overheads that AnyEvent adds 1282To give you an idea of the performance and overheads that AnyEvent adds
1121of various event loops I prepared some benchmarks. 1284of various event loops I prepared some benchmarks.
1122 1285
1123=head2 BENCHMARKING ANYEVENT OVERHEAD 1286=head2 BENCHMARKING ANYEVENT OVERHEAD
1124 1287
1125Here is a benchmark of various supported event models used natively and 1288Here is a benchmark of various supported event models used natively and
1126through anyevent. The benchmark creates a lot of timers (with a zero 1289through AnyEvent. The benchmark creates a lot of timers (with a zero
1127timeout) and I/O watchers (watching STDOUT, a pty, to become writable, 1290timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1128which it is), lets them fire exactly once and destroys them again. 1291which it is), lets them fire exactly once and destroys them again.
1129 1292
1130Source code for this benchmark is found as F<eg/bench> in the AnyEvent 1293Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1131distribution. 1294distribution.
1148all watchers, to avoid adding memory overhead. That means closure creation 1311all watchers, to avoid adding memory overhead. That means closure creation
1149and memory usage is not included in the figures. 1312and memory usage is not included in the figures.
1150 1313
1151I<invoke> is the time, in microseconds, used to invoke a simple 1314I<invoke> is the time, in microseconds, used to invoke a simple
1152callback. The callback simply counts down a Perl variable and after it was 1315callback. The callback simply counts down a Perl variable and after it was
1153invoked "watcher" times, it would C<< ->broadcast >> a condvar once to 1316invoked "watcher" times, it would C<< ->send >> a condvar once to
1154signal the end of this phase. 1317signal the end of this phase.
1155 1318
1156I<destroy> is the time, in microseconds, that it takes to destroy a single 1319I<destroy> is the time, in microseconds, that it takes to destroy a single
1157watcher. 1320watcher.
1158 1321
1254 1417
1255=back 1418=back
1256 1419
1257=head2 BENCHMARKING THE LARGE SERVER CASE 1420=head2 BENCHMARKING THE LARGE SERVER CASE
1258 1421
1259This benchmark atcually benchmarks the event loop itself. It works by 1422This benchmark actually benchmarks the event loop itself. It works by
1260creating a number of "servers": each server consists of a socketpair, a 1423creating a number of "servers": each server consists of a socket pair, a
1261timeout watcher that gets reset on activity (but never fires), and an I/O 1424timeout watcher that gets reset on activity (but never fires), and an I/O
1262watcher waiting for input on one side of the socket. Each time the socket 1425watcher waiting for input on one side of the socket. Each time the socket
1263watcher reads a byte it will write that byte to a random other "server". 1426watcher reads a byte it will write that byte to a random other "server".
1264 1427
1265The effect is that there will be a lot of I/O watchers, only part of which 1428The effect is that there will be a lot of I/O watchers, only part of which
1266are active at any one point (so there is a constant number of active 1429are active at any one point (so there is a constant number of active
1267fds for each loop iterstaion, but which fds these are is random). The 1430fds for each loop iteration, but which fds these are is random). The
1268timeout is reset each time something is read because that reflects how 1431timeout is reset each time something is read because that reflects how
1269most timeouts work (and puts extra pressure on the event loops). 1432most timeouts work (and puts extra pressure on the event loops).
1270 1433
1271In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100 1434In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1272(1%) are active. This mirrors the activity of large servers with many 1435(1%) are active. This mirrors the activity of large servers with many
1273connections, most of which are idle at any one point in time. 1436connections, most of which are idle at any one point in time.
1274 1437
1275Source code for this benchmark is found as F<eg/bench2> in the AnyEvent 1438Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1276distribution. 1439distribution.
1278=head3 Explanation of the columns 1441=head3 Explanation of the columns
1279 1442
1280I<sockets> is the number of sockets, and twice the number of "servers" (as 1443I<sockets> is the number of sockets, and twice the number of "servers" (as
1281each server has a read and write socket end). 1444each server has a read and write socket end).
1282 1445
1283I<create> is the time it takes to create a socketpair (which is 1446I<create> is the time it takes to create a socket pair (which is
1284nontrivial) and two watchers: an I/O watcher and a timeout watcher. 1447nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1285 1448
1286I<request>, the most important value, is the time it takes to handle a 1449I<request>, the most important value, is the time it takes to handle a
1287single "request", that is, reading the token from the pipe and forwarding 1450single "request", that is, reading the token from the pipe and forwarding
1288it to another server. This includes deleting the old timeout and creating 1451it to another server. This includes deleting the old timeout and creating
1361speed most when you have lots of watchers, not when you only have a few of 1524speed most when you have lots of watchers, not when you only have a few of
1362them). 1525them).
1363 1526
1364EV is again fastest. 1527EV is again fastest.
1365 1528
1366Perl again comes second. It is noticably faster than the C-based event 1529Perl again comes second. It is noticeably faster than the C-based event
1367loops Event and Glib, although the difference is too small to really 1530loops Event and Glib, although the difference is too small to really
1368matter. 1531matter.
1369 1532
1370POE also performs much better in this case, but is is still far behind the 1533POE also performs much better in this case, but is is still far behind the
1371others. 1534others.
1411probably even less useful to an attacker than PERL_ANYEVENT_MODEL). 1574probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1412 1575
1413 1576
1414=head1 SEE ALSO 1577=head1 SEE ALSO
1415 1578
1579Utility functions: L<AnyEvent::Util>.
1580
1416Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>, 1581Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1417L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. 1582L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1418 1583
1419Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>, 1584Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1420L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, 1585L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1421L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>, 1586L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1422L<AnyEvent::Impl::POE>. 1587L<AnyEvent::Impl::POE>.
1423 1588
1589Non-blocking file handles, sockets, TCP clients and
1590servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
1591
1592Asynchronous DNS: L<AnyEvent::DNS>.
1593
1424Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>, 1594Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1425 1595
1426Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>. 1596Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1427 1597
1428 1598
1429=head1 AUTHOR 1599=head1 AUTHOR
1430 1600
1431 Marc Lehmann <schmorp@schmorp.de> 1601 Marc Lehmann <schmorp@schmorp.de>

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